Complexometric precursor formulation methodology for industrial production of fine and ultrafine powders and nanopowders for lithium metal oxides for battery applications

ABSTRACT

A compound M j X p  which is particularly suitable for use in a battery prepared by the complexometric precursor formulation methodology wherein: M j  is at least one positive ion selected from the group consisting of alkali metals, alkaline earth metals and transition metals and j is an integer representing the moles of said positive ion per moles of said M j X p ; and X p , a negative anion or polyanion from Groups IIIA, IV A, VA, VIA and VIIA and may be one or more anion or polyanion and p is an integer representing the moles of said negative ion per moles of said M j X p .

BACKGROUND

The present application is related to an improved method of forming fineand ultrafine powders and nanopowders. More specifically, the presentinvention is related to the formation of fine and ultrafine powders andnanopowders through complexometric precursors formed on bubble surfaces.Furthermore, this invention describes the preparation of lithium metaloxide by complexometric precursors that have excellent physical andchemical properties required for high performance battery applications.

Our present society is advancing very rapidly in new technologiesespecially in the areas of biotechnology, medicine, electronics,pharmaceuticals and energy. These require significant improvements inraw material processing and in the production of high performanceproducts of advanced chemical formulations without compromising costrelative to commercial scale-up for industrial production (FIG. 1).Thus, this requires a combination of structure-processing-propertycorrelations that will lead to specialized high performance materials inorder to sustain these modern technically demanding criteria.

Starting with a desired specific application, the process must betailored to obtain the characteristics, both physical and chemical, inorder to meet the end performance result. It is imperative to uniquelycombine both well-established properties of the compounds and/or rawmaterials with the new, unique, unusual or desirable properties of theadvanced materials. For example, traditional ceramics are well-known tobe electrical insulators yet it is possible to utilize this propertysuch that the special ceramics will provide high thermal conductivityallowing their use as heat sinks in substrates for microelectronics.Ceramic composites of inorganic glass fibers and plastics have been usedfor thermal and sound insulation traditionally but now are also used asoptical fibers replacing the traditional copper wire. Ceramic enginesreplacing the traditional steel engines can withstand highertemperatures and will burn energy more effectively. This requires thatthe ceramics used for engine manufacture be of very fine particles suchthat strength and toughness to withstand the elevated temperatures andruggedness required for these applications. Furthermore, nanosizepowders when fabricated into the ceramic parts for these vehicles willbe more dense, have less defects, and can be fabricated in thinner andsmaller, lightweight sizes for practical use.

Increased energy consumption today necessitates discovery of newresources but also improvement in current materials to satisfy theenergy infrastructure such as solar cells, fuel cells, biofuels, andrechargeable batteries. For example, the lithium ion battery that hasbeen in use in consumer electronic devices but is now commanding asignificant role in larger transport vehicles. These alternative energyresources must be more practical, and price competitive with fossilfuels, for wider acceptability in high-performance applications. As aconsequence, sophisticated devices require specially designedmicrostructures that will enhance the physical and chemical propertiesof the materials utilized. Often, these materials are more expensive toproduce on an industrial scale. Furthermore, these specialty powderedmaterials such as oxides, phosphates, silicates and the like, requirenot only a nanosize material but also a narrow particle sizedistribution with high porosity, high surface area and othercharacteristics to achieve enhanced performance. For instance, ananostructured lithium cathode powder for the lithium ion battery wouldbe expected to have improved mass and charge transport due to shorterdiffusion paths and higher amount of active sites resulting from itsfiner smaller particle size. However, this added cost for the addedvalue may not be acceptable to the end consumer resulting in reducedsales.

Other challenges are medical applications such as the use of calciumphosphate for bone substitution. While several calcium phosphate powdersare available in the market, the requirements of less than one microndiscrete particles as described in U.S. Pat. No. 8,329,762 B2 areimportant for making a biocompatible synthetic bone. U.S. Pat. No.5,714,103 describes bone implants based on calcium phosphate hydrauliccements, called CHPCs, made of a succession of stacked layers with amacroporous architecture mimicking the natural porosity of spongiousbone. This medical field would definitely benefit from improved powderswith better performance and lower cost. Another example is a dermalpatch wherein the pharmaceutical drug is released to the body. Bothdermal patch and drug material combined would be more compatible iftheir particle sizes were nanosize with narrow particle sizedistribution. Nanopowders can also significantly impact high performancedental applications, for example, such as teeth filling materials aswell as enamel coating materials to aesthetically enhance and strengthenthe tooth structure. In order to widen the usage of nanomaterials in themedical field, both cost and performance value should be compatible toboth producer and end-user.

Distinctive characteristics clearly differentiate between advancedmaterials and traditional materials in several aspects, notably in rawmaterials, processing, chemical and physical characteristics, novelapplications and specialized markets. Conventional powder processes aremade without strict chemical control and are generally made fromgrinding and segregating naturally occurring materials through physicalmeans. These result in neither ultrapure nor ultrahomogeneous particlessuch that fabrication of a product using such heterogeneous and impuresubstances gives grain boundary impurities that may reduce mechanicalstrength or optical deformations and other limitations. Chemicalprocessing solves this problem by controlling the composition of thepowder at the molecular level to achieve a special ultrastructure forthe preferred performance application. Specialized properties such asconductivity, electrochemical capacity, optical clarity, dielectricvalue, magnetic strength, toughness and strength are met only withspecialized processing methods to control microstructure. However, thesedemands necessitate an economically commercial viable process for largescale production. The dual requirements of cost and performance must bemet to successfully commercialize these advanced materials.

A significant improvement in available raw materials is needed to meetmany objectives. One objective is high purity, no longer 90% but >99%and even 99.999%, which entails chemical processing to removeundesirable impurities that affect performance. Another objective isparticle size which preferably has a narrow, homogeneous particle sizedistribution with finer particle sizes of no longer 50 microns but 1micron and preferably, nanosize. The addition of dopants which aredeemed to enhance the specialized properties, like electronicconductivity and others, must be homogeneously distributed but alsopreferably distributed on the surface of the powder in someapplications. Cobalt, aluminum and gadolinium are suitable dopants.Other dopants include Ti, Zr, Mg, Ca, Sr, Ba, Mg, Cr and B.

Innovations in processing these advanced materials to the final productare also necessary. As such, combinations of different processingtechniques are often utilized. For example, inorganic powders have beenusually made by traditional ceramics like solid state sintering.However, the resulting powder obtained by this method alone generallyhas a wider and larger particle size distribution. To obtain ahomogeneous nanosize distribution, several grinding and milling stepshave been employed. The generic types are ball mills, rod mills,vibratory mills, attrition mills, and jet mills. Disadvantages of thesemethods include energy and labor intensive production cycles andpossibility of contamination from grinding balls utilized. Defects inthe microstructure also occur causing degradation in the requiredperformance targets. Chemical vapor deposition, emulsion evaporation,precipitation methods, hydrothermal synthesis, sol-gel, precipitation,spray drying, spray pyrolysis and freeze drying are some of the othermethods used for these types of preparations, each with advantages anddisadvantages.

The technical drivers today call for particles less than one micron, andeven to less than 100 nanometers. To date, the significance of theinitial powder synthesis steps have been overlooked but these initialreactions clearly define the final finished powder microstructure andalso determines scalability controls and finally, cost and performance.Careful selection of the starting reactants and the media—solid, liquidor gas—plays a unique role in the formulation of low cost, highperformance powders.

An example is the formation of colloidal consolidated structures byinitial dispersion of particles in a liquid medium. When the particleconcentration is low, dispersed colloidal suspensions can be used toeliminate flow units larger than a certain size through sedimentation orclassification. The surface chemistry of the particles can be modifiedthrough the adsorption of surfactants. The mixing of multiphase systemscan be achieved at the scale of the primary particle size. Once thedesired modifications are achieved, the transition from dispersed toconsolidated structure is accomplished by either increasing theparticle-particle attraction forces, such as by flocculation, or byincreasing the solids content of the suspension for forced flocculation.This whole process results in going from a fluid state (“slip”) to asolid phase transition (“cast”). While this has been found to occur inthe micron to sub-micron size range, highly concentrated suspensionswith nanometer size particles have not been as successful. Thus, someinnovation is needed in traditional colloidal techniques in order toachieve nanosize powders.

Such nanoparticles possess crystalline properties and other nanoscalefeatures that dramatically result in unique mechanical, magnetic,thermal, optical, biological, chemical and electrical properties.Considerable growth is expected in all these markets. Therefore,achievement of an economically viable industrial production of thesespecialized materials entails innovations in conventional processingtechniques and distinct improvements in present industrial equipment.

Traditionally, powders are made using a solid state route. By thismethod, the raw materials are ground and milled to the same size andwith a narrow size distribution, blended and fired to obtain the finalproduct as shown:A solid+B solid→C solid product

In U.S. Pat. No. 6,277,521 B1, Manev et al. describe the preparation oflithium metal oxides such as LiNi_(1−x)Co_(y)M_(α)M′_(β)O₂ where M is Tior Zr and M′ is Mg, Ca, Sr, Ba, and combinations thereof. To prepareLiNi_(0.7)Co_(0.2)Ti_(0.05)Mg_(0.05)O₂, stoichiometric amounts off LiOH,NiO, Co₃O₄, TiO₂ and Mg(OH)₂ are weighed, mixed and fired for 10 hoursat 550° C. followed for an additional 10 hours at 800° C. Milling afterthe firing step is done to produce the fine powders of micron size.Furthermore, to obtain a narrow particle distribution, sizing selectionis also done in line with the milling step. Larger size fractions arethen re-milled.

One of the problems with obtaining nanopowders via the solid statemethod is the considerable milling process that can be time and laborintensive. The quality of the final product is a function of time,temperature and milling energy. Achieving nanometer grain sizes ofnarrow size distribution requires relatively long processing times insmaller batches, not just for the final sintered product but also forthe starting materials, as these materials should have particle sizeswithin the same distribution for them to blend more homogeneously inorder to have the right stoichiometry in the final product. Hence, itmay become necessary to correct the stoichiometries of the final productafter firing by reblending additional starting raw materials and thenrefiring. As a result, successive calcinations make the processing timelonger and more energy intensive which increases production cost.Production of nanopowders by mechanical attrition is a structuraldecomposition of the coarser grains by severe plastic deformationinstead of by controlled cluster assembly that yields not only the rightparticle size and the required homogeneous narrow size distribution butalso significant nanostructures or microstructures needed for effectiveperformance benchmarks. As such, some higher performance standardsrequired for specialized applications are not attained. C. C. Kochaddresses these issues in his article “Synthesis of NanostructuredMaterials by Mechanical Milling Problems and Opportunities”,Nanostructured Materials, Vol. 9, pp 13-22, 1997.

Obtaining fine powders and nanopowders by milling has improved withmodern grinding machines such as stirred ball mills and vibration millsfor wet grinding or jet mills for dry grinding processes. However,achieving a narrow particle size distribution still remains a difficulttask today. Classifiers have to be integrated with the milling systemand this repetitive sizing and milling procedures increase theprocessing time in making fine powders and even much longer fornanopowders. Another drawback is potential contamination of the finalproduct from the milling media used. U.S. Pat. No. 7,578,457 B2, to R.Dobbs uses grinding media, ranging in size from 0.5 micron to 100 mm indiameter, formed from a multi-carbide material consisting of two or morecarbide forming elements and carbon. These elements are selected fromthe group consisting of Cr, Hf, Nb, Ta, Ti, W, Mo, V, Zr. In US PatentApplication No. 2009/0212267 A1, a method for making small particles foruse as electrodes comprises using a first particle precursor and asecond particle precursor, milling each of these precursors to anaverage size of less than 100 nm before reacting to at least 500° C. Asan example, to make lithium iron phosphate, one precursor is aluminumnitrate, ammonium dihydrogen phosphate and the like and the otherprecursor is lithium carbonate, lithium dihydrogen phosphate and thelike. In US Patent Application No. 2008/0280141 A1, grinding media withdensity greater than 8 g/mL and media size from 75-150 microns wasspecially made for the desired nanosize specification and the hardnessof the powder to be milled. The premise is that finer, smaller size,specialized grinding media can deliver the preferred nanosize particles.Time and energy consumption are high using this modified solid stateroute to nanopowders. Moreover, after milling, the grinding media andthe nanopowders must be separated. Since nanopowders are a health riskif inhaled, the separation will have to be done under wet conditions.The wet powders will then have to be dried again which adds to thenumber of processing steps.

Chemical vapor deposition, physical vapor deposition, plasma synthesisare all synthesis of powders in the gas phase. In this process, thestarting raw materials are vaporized in the gas phase then collected ina cooling step on a chosen substrate. Controlled nucleation yieldsexcellent powders that easily meet the rigorous requirements forspecialized applications but the cost of the energy source and theequipment required for this method can significantly impact the finalcost of the powder. More information on these processes is discussed byH. H. Hahn in “Gas Phase Synthesis of Nanocrystalline Materials,“Nanostructured Materials, Vol. 9, pp 3-12, 1997. Powders for thesemiconductor industry are usually made by this type of processing.

In U.S. Pat. No. 8,147,793 B2, S. Put et al. disclose a method ofpreparing nano-sized metal bearing powders and doped powders by using anon-volatile metal bearing precursor and dispersing this precursor in ahot gas stream. This hot gas stream may be generated by a flame burneror a DC plasma arc with nitrogen as a plasma gas, for example. Thus,coarse size ZnO powder that is injected is reduced to Zn vapor. When airis introduced, Zn is oxidized to ZnO with nano-size particles.

Among the wet solution methods for fine powder synthesis areprecipitation, sol-gel, and variants of these using complexing agents,emulsifiers and/or surfactants. In WO 2010/042434 A2, Venkatachalam etal. describe a co-precipitation process involving metal hydroxides andsol-gel approaches for the preparation ofLi_(1+x)Ni_(α)Mn_(β)Co_(γ)M_(δ)O_(2−α)F_(z) where M is Mg, Zn, Al, Ga,B, Zr, Ca, Ce, Ti, Nb or combinations thereof. In one example cited,stoichiometric amounts of nickel acetate, cobalt acetate, and manganeseacetate were dissolved in distilled water to form a mixed metal acetatesolution under oxygen-free atmosphere. This mixed metal acetate solutionwas added to a stirred solution of lithium hydroxide to precipitate themixed metal hydroxides. After filtration, washing to remove residual Liand base, and drying under nitrogen atmosphere, the mixed metalhydroxides were mixed with the appropriate amount of lithium hydroxidepowder in a jar mill, double planetary mixer or a dry powder mixer. Themixed powders were calcined at 400° C. for 8 hours in air, cooling,additional mixing, homogenizing in the mill or mixer, and thenrecalcined at 900° C. for 12 hours to form the final productLi_(1.2)Ni_(0.175)Co_(0.10)Mn_(0.525)O₂. The total time from start tofinish for their method is 20 hours for the calcination step alone plusthe cooling time, the times for the initial mixed metal hydroxideprecipitation, milling and blending to homogenize, and the filtrationand washing steps. All these process steps add up to a calcination timeof 20 hours excluding the cooling time for the furnace and the time fromthe other processing steps which will have a combined total of at least30 hours or more. Furthermore, in their process, the second part afterthe co-precipitation is a solid state method since the mixed metalhydroxides and the lithium hydroxides are mixed and then fired. Thefinal calcined powder size obtained from a solid state route is usuallyin the micron size range which will entail additional intensive millingto reduce the particles to a homogeneous narrow size distribution ofnanopowders. This processing has numerous steps to obtain the finalproduct which can impact large scale production costs.

Another example of co-precipitation is described in U.S. Pat. No.6,241,959 B1. Nitrates of nickel, cobalt and magnesium were mixed in amole ratio of 0.79:0.19:0.02 and dissolved in solution. Aqueous ammoniawas added to precipitate the hydroxides and the pH was further adjustedusing 6M NaOH till pH 11. After 6 hours of addition time, the Ni—Cocomposite hydroxide was separated. Lithium hydroxide was mixed with thisNi—Co hydroxide and heated to 400° C. and maintained at this temperaturefor 6 hours. After cooling, the product was then reheated to 750° C. for16 hours. The battery cycling test was done at a low C rate of 0.2 C.Discharge capacity was 160 mAh/g. Only 30 cycles were shown. Note thatthe coprecipitation process is only for the Ni—Co hydroxides. The secondpart of this process is a solid state synthesis where the starting rawmaterials, Ni—Co hydroxide and the lithium hydroxide are mixed and thenfired. The addition of NaOH to raise the pH to 11 as well as provide asource of hydroxide ions would leave residual Na ions in the finalproduct unless the excess Na⁺ is washed off. This excess Na⁺ will affectthe purity of the material and have some deleterious effect in thebattery performance. The total process time is 6 hours addition time forthe co-precipitation step, 22 total hours for the holding time at thetwo heating steps and additional time for the other steps of cooling,separating, mixing and others which sums up to at least 40 hours ofprocessing time.

Sol-gel synthesis is a variant of the precipitation method. Thisinvolves hydrolysis followed by condensation to form uniform finepowders. The raw materials are expensive and the reaction is slow sincethe hydrolysis-condensation reactions must be carefully controlled.Alkoxides are usually the choice and these are also air sensitive; thusrequiring the reactions to be under controlled atmosphere.

Hydrothermal synthesis has also been used to prepare these powders. Thisinvolves crystallization of aqueous solutions at high temperature andhigh pressures. An example of this process is disclosed in US PatentPublication No. 2010/0227221 A1. A lithium metal composite oxide wasprepared by mixing an aqueous solution of one or more transition metalcations with an alkalifying agent and another lithium compound toprecipitate the hydroxides. Water is then added to this mixture undersupercritical or subcritical conditions, dried then followed bycalcining and granulating then another calcining step to synthesize thelithium metal oxide. The water under supercritical or subcriticalconditions has a pressure of 180-550 bar and a temperature of 200-700°C.

The use of agents like emulsifiers, surfactants, and complexing agentsto form nanosize powders has been demonstrated. In microemulsionmethods, inorganic reactions are confined to aqueous domains calledwater-in-oil or surfactant/water/oil combination. A problem isseparation of the product particle from the oil since filtration of ananosize particle is difficult. Reaction times are long. Residual oiland surfactant that remain after the separation still have to be removedby other means such as heating. As a result, the batch sizes are small.

A variety of structures are formed by the surfactant with anotherparticle dispersed in solution. Micelles are formed at highconcentrations of the surfactant and the micelle diameter is determinedby the length of the surfactant chain which can be from 20-300angstroms. U.S. Pat. No. 6,752,979 B1 describes a way of making metaloxide particles with nano-sized grains using surfactants. A concentratedaqueous solution of at least one or more metal cations of at least 90%of its solubility is mixed with surfactant to form micelles at a giventemperature. Optionally, this micellar liquid forms a gel. This mixtureis heated to form the metal oxide and remove the surfactant. Adisadvantage is the long heat treatment times.

U.S. Pat. No. 6,383,285 B1 discloses a method for making cathodematerials for lithium ion batteries using a lithium salt, a transitionmetal salt, and a complexing agent in water then removing water byspray-drying to form a precursor. These complexing agents were citricacid, oxalic acid, malonic acid, tartaric acid, maleic acid and succinicacid. The use of these agents increases the processing cost of theproduct. The precursor is formed from the lithium, transition metal andthe complexing agent after spray drying. Battery capacities were onlygiven for the first cycle. The C-rate was not defined. For electricvehicle applications, lithium ion battery performance at high C-rate formany cycles is an important criterion.

A method for making lithium vanadium phosphate was described in USPatent Publication No. 2009/0148377 A1. A phosphate ion source, alithium compound, V₂O₅, a polymeric material, solvent, and a source ofcarbon or organic material were mixed to form a slurry. This wet blendedslurry was then spray dried to form a precursor which was then milled,compacted, pre-baked and calcined for about 8 hours at 900° C. Theparticle size after spray drying was about 50-100 microns. The finalproduct was milled to 20 microns using a fluidized bed jet mill.

Nanosize Li₄Ti₅O₁₂ was prepared by preparing this lithium titanate as afirst size between 5 nm to 2000 nm as described in U.S. Pat. No.6,890,510 B2 from a blend of titanium and lithium, evaporating andcalcining this blend, milling this powder to a finer size, spray dryingthen refiring this lithium titanate, then milling again. There areseveral milling and firing sequences in this process to obtain thenanosize desired which increase the number of processing steps whichconsequently increases the cost of processing.

Lithium ion batteries have proven their commercial practicality sincethe early 1990s when Sony first introduced this battery for its consumerelectronics. The cathode material used then was lithium cobalt oxidewhose layered structure allowed the Li+ ions to effectively intercalatebetween the cathode and the anode. Moreover, the battery was lightweightand without any memory effect, compared with the other rechargeablebatteries like the NiCd or the NiMH batteries. Its energy density was3-4 times more than currently available rechargeable batteries.

The start of commercialization of the lithium ion battery using lithiumcobalt oxide has benefited many applications. Its reputation for safetyin consumer devices has promoted other potential applications, mostnotably in the transportation industry. Our current consumption of oilhas increased significantly and such dependence has spurred moreinvestigation into alternative sources of energy. That direction focusedinto developing the lithium ion battery for high load, high powerapplications and this required developing and investigating newmaterials for use as a cathode for the lithium ion battery. Attentionwas generated towards research into the cost, safety and reliability oflithium cathode materials.

The first row of transition metals and those similar to the cobalt ionin chemical and physical properties were Ni, Mn and Fe as well as V.These compounds were synthesized generally using the traditional solidstate route. Nickel is a good substitute for cobalt and has a layeredstructure. Its use in the NiCd and NiMH rechargeable batteries hasproven its capability. However, its excellent conductivity also causedsome safety problems in the lithium ion battery. Cobalt is an expensivemetal but has proven reliability by its established battery performancein commercial lithium ion batteries for many years. Manganese, as aspinel structure LiMn₂O₄, is least expensive but it has a disadvantageof not having high conductivity. Iron as LiFeO₂ did not have the batteryperformance required but as olivine structure LiFePO₄, it has proven itsuse in high power applications. A layered-layered structure,xLiMn₂O₃.(1−x)LMO₂, where M=Co,Ni,Mnhas taken considerable interest since it has exhibited good batteryperformance. Other research is ongoing extensively on combinations ofCo, Ni, Mn and Fe, including the addition of dopants or coatings tocreate some surface modifications that would lead to thermal stabilityand/or chemical stability which would then extend cycle life.

Today, synthesizing an alternative lithium metal oxide or other lithiummetal compound as cathode material for electric vehicle applicationsremains a chemical challenge. The transportation requirements aresignificantly more demanding than consumer electronic devices. Theseissues include cycle life especially under extreme temperatureconditions, charging times, miles driven per charge, miles driven percharge per speed, total vehicle battery cost, battery cycle life,durability, and safety. The preferred lithium cathode material will haveto be produced industrially in large scale. Therefore, the processingconditions must produce the physical and chemical characteristics ofthis preferred lithium cathode material at low cost. Starting materialsshould be of high purity, preferably with low Na, Cl and S and othercontaminants detrimental to the battery yet be low cost. Productionequipment must be currently available equipment already in use withnovel innovations easily implemented. Finally, the number of processingsteps should be decreased as well as be less energy and labor intensive.

The desired properties of this preferred lithium cathode material are;namely: 1.) high capacity, 2.) long cycle life, 3.) high stability, 4.)fast charging rate, 5.) low cost. The physical properties should includethe following; namely: 1.) fine particle size, 2.) narrow particle sizedistribution, 3.) uniform morphology, 4.) high purity, 5.) high surfacearea, 6.) optimum degree of crystallization, 7.) minimum defects and 8.)minimum agglomeration. In order to achieve all these at low cost oracceptable consumer cost requires a balance in the preparation of thispreferred lithium cathode. Nanoparticles have been of significantinterest but the cost of achieving nanosize powders remains asignificant cost in production.

This invention aims to achieve this preferred high performance lithiumcathode material by using the complexometric precursor formulationmethodology in the synthesis of this lithium cathode material. Theresults described in this invention show that the materials produced bya complexcelle formed during the CPF process outperform cathodescurrently in commercial use. The objective is to industrially andcost-effectively produce these preferred lithium cathode nanomaterialsfor energy storage systems by the complexometric precursor formulationmethodology. As such, new avenues in battery technology will open and beeasily commercialized. Furthermore, these novel nanomaterials will havean impact in other future energy systems and other potentialapplications in other industries.

SUMMARY OF THE INVENTION

It is the objective of this invention to describe an economicallyscalable process useful for several high value-added inorganic powderstailored to meet the desired performance specifications. It is a furtherobjective of this invention to produce the selected narrow size particledistribution of these powders and to produce the desired particle sizeneeded for the selected application, such size ranging from fine micronsize particles to ultrafine powders and the nanosize powders. It is alsothe objective of this invention to produce these powders that meet orexceed the performance of presently available materials. It is theobjective of this invention to prepare lithium metal oxide powders bycomplexometric precursor formulation methodology to achieve tailoredphysical and chemical properties for high performance lithium batteryapplications.

It is an object of this invention to provide a methodology forindustrial production of special fine, ultrafine and nano powderswithout compromising performance.

A particular advantage of the invention is the ability to prepare fine,ultrafine and nano-powders in large scale production.

It is an object of the invention to produce these specialized powdersthat outperform presently available powders.

It is an object of the invention to utilize low cost starting rawmaterials and to incorporate any purification within the process stepsas required.

These and other advantages, as will be realized, are provided in amethod of forming a powder M_(j)X_(p) wherein M_(j) is a positive ion orseveral positive ions selected from alkali metal, alkaline earth metalor transition metal; and X_(p) is a monoatomic or a polyatomic anionselected from Groups IIIA, IVA, VA, VIA or VIIA; called complexometricprecursor formulation or CPF. The method includes the steps of:

-   providing a first reactor vessel with a first gas diffuser and a    first agitator;-   providing a second reactor vessel with a second gas diffuser and a    second agitator;-   charging the first reactor vessel with a first solution comprising a    first salt of M_(j)X_(p);-   introducing gas into the first solution through the first gas    diffuser,-   charging the second reactor vessel with a second solution comprising    a second salt of M_(j)X_(p);-   adding the second solution to the first solution to form a    complexcelle;-   drying the complexcelle, to obtain a dry powder; and-   calcining the dried powder of said M_(j)X_(p).

Yet another embodiment is provided in a compound M_(j)X_(p) prepared bythe complexometric precursor formulation methodology wherein:

-   M_(j) is at least one positive ion selected from the group    consisting of alkali metals, alkaline earth metals and transition    metals and n is an integer representing the moles of said positive    ion per moles of said M_(j)X_(p); and-   X_(p), a negative anion or polyanion from Groups IIIA, IV A, VA, VIA    and VIIA and may be one or more anion or polyanion and p is an    integer representing the moles of said negative ion per moles of    said M_(j)X_(p).

FIGURES

FIG. 1 is a diagram of advanced technical materials which requirespecialized processing to obtain composites, whiskers, fibers andpowders.

FIG. 2 is a comparison of preparative methods for powders.

FIG. 3 is a flow chart of two reactants via the complexometric precursorformulation methodology for the synthesis of specialized powders.

FIG. 4 illustrates a reactor vessel with gas inlet tubes and agitatorwith special blades.

FIG. 5A schematically illustrates agitator blades with wound concentricrings.

FIG. 5B is a side schematic partial view of the concentric rings of theagitator blade.

FIG. 5C schematically illustrates one set of propellers with threeblades, concentric rings are not shown, attached to the mixer shaft,each blade rotating on its own axis horizontally and vertically on themixer axis.

FIG. 5D schematically illustrates two sets of propellers with threeblades arranged on the mixer shaft.

FIG. 5E schematically illustrates one set of propellers with threeblades arranges alternately on the mixer shaft.

FIG. 5F schematically illustrates one set of propellers with four bladeson the mixer shaft.

FIG. 5G schematically illustrates one set of propellers with four bladesarranged alternately on the shaft of the reactor.

FIG. 6A schematically illustrates a bubble surface above the bulk of thesolution showing small and large bubbles.

FIG. 6B is a top schematic view of the bubble surface interface showingthe reactants on the surface interface.

FIG. 7 is a schematic representation of the steps during complexcelleformation and separation from the bulk of the solution.

FIG. 8A is a scanning electron micrograph at 5000× of a commercialLiCoO₂ in Example 1.

FIG. 8B is a scanning electron micrograph at 25000× of a commercialLiCoO₂ in Example 1.

FIG. 9 is an x-ray powder diffraction pattern of a commercial LiCoO₂ inExample 1.

FIG. 10 is a scanning electron micrograph at 5000× of air dried LiCoO₂feed precursor to the spray dryer for Example 2.

FIG. 11A is a scanning electron micrograph at 10000× of spray driedLiCoO₂ described in Example 2 prior to calcination.

FIG. 11B is a scanning electron micrograph at 25000× of spray driedLiCoO2 described in Example 2 prior to calcination.

FIG. 12 is a scanning electron micrograph at 10000× of spray driedLiCoO₂ described in Example 2 after calcination.

FIG. 13 is an x-ray powder diffraction pattern of LiCoO₂ in Example 1.

FIG. 14 is battery cycling data for Examples 1 and 2 at C/20 for 500cycles.

FIG. 15 is battery cycling data at 1 C for 500 cycles for Examples 1 and2 after recalcination for 5 h at 900° C.

FIG. 16 is a scanning electron micrograph at 10000× of recalcined LiCoO₂from Example 2.

FIG. 17 is a scanning electron micrograph at 10000× of recalcinedcommercial LiCoO₂ from Example 1.

FIG. 18A is a scanning electron micrograph at 2000× of air-driedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4.

FIG. 18B is a scanning electron micrograph at 10000× of air-driedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4.

FIG. 19A is a scanning electron micrograph at 5000× of spray driedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4.

FIG. 19B is a scanning electron micrograph at 10000× of spray driedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4.

FIG. 20A is a scanning electron micrograph at 10000× of calcinedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4.

FIG. 20B is a scanning electron micrograph at 25000× of calcinedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4.

FIG. 21 is an x-ray powder diffraction pattern of calcinedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4.

FIG. 22 is battery Cycling Data for calcinedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4 at RT for 500cycles at 1 C.

FIG. 23A is battery Cycling Data for calcinedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4 at 30° C. for 500cycles at different C rates from C/20 to 1 C.

FIG. 23B is battery Cycling Data for calcinedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4 at 30° C. for 500cycles at different C rates from C/10, C/3 and 1 C.

FIG. 24A is battery Cycling Data for calcinedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4 at 25° C. for 500cycles at from C/20 to 1 C.

FIG. 24B is battery Cycling Data for calcinedLi_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ from Example 4 at 25° C. for 500cycles at 1 C.

FIG. 25A is a scanning electron micrograph at 2000× of spray driedLiCoO₂ from Example 6.

FIG. 25B is a scanning electron micrograph at 10000× of spray driedLiCoO₂ from Example 6.

FIG. 26 is a scanning electron micrograph at 10000× of calcined LiCoO₂from Example 6.

FIG. 27 is an X-ray powder diffraction pattern of LiCoO₂ in Example 6.

FIG. 28 is the battery cycling data for LiCoO₂ of Example 6 at C/20 for50 cycles.

FIG. 29 is an X-ray powder diffraction pattern of LiCoO₂ aftercalcination for 5 h at 900° C. in Example 7.

FIG. 30A is a scanning electron micrograph at 5000× of calcined LiCoO₂from Example 7.

FIG. 30B is a scanning electron micrograph at 10000× of calcined LiCoO₂from Example 7.

FIG. 30C is a scanning electron micrograph at 25000× of calcined LiCoO₂from Example 7.

FIG. 31 is the battery cycling data for LiCoO₂ of Example 7 and thecommercial sample at 1 C for 500 cycles at RT.

FIG. 32 is an X-ray powder diffraction pattern of LiCoO₂ fired two timesfor 5 h at 900° C. in Example 8.

FIG. 33A is a scanning electron micrograph at 5000× of recalcined LiCoO₂from Example 8.

FIG. 33B is a scanning electron micrograph at 10000× of recalcinedLiCoO₂ from Example 8.

FIG. 33C is a scanning electron micrograph at 25000× of recalcinedLiCoO₂ from Example 8.

FIG. 34 is the battery cycling data for LiCoO₂ of Example 8 and therefired commercial sample in Example 3 at 1 C for 500 cycles at RT.

DESCRIPTION

The instant invention is specific to an improved method of formingnanoparticles. More specifically, the instant invention is specific to amethod of forming particles through formation of a complexometricprecursor formed on a bubble surface thereby allowing for carefulcontrol of nucleation and crystal growth.

The invention will be described with reference to the various figureswhich form an integral non-limiting component of the disclosure.Throughout the disclosure similar elements will be numbered accordingly.

This invention described herein is a complexometric precursorformulation methodology, hereinafter referred to as “CPF”, suitable forlarge scale industrial production of high performance fine, ultrafineand nanosize powders requiring defined unique chemical and physicalproperties that are essential to meet performance specifications forspecialized applications.

A particularly suitable material formed by the CPF process is a lithiumnickel manganese cobalt compound defined by formula isLi_(2−x−y−z)Ni_(x)Mn_(y)Co_(z)O₂ wherein x+y+z≦1 and at least one of x,y or z is not zero and more preferably none of x, y or z is zero.

The CPF method proceeds in the formation of a complex precursor, hereincalled complexcelle, on a bubble surface thereby providing for thecontrolled formation of specialized microstructures or nanostructuresand a final product with particle size, surface area, porosity, phasepurity, chemical purity and other essential characteristics tailored tosatisfy performance specifications. Powders produced by CPF are obtainedwith a reduced number of processing steps relative to currently usedtechnology and can utilize presently available industrial equipment. CPFis simple to implement and preferred design configurations are furtherdescribed and illustrated in FIGS. 4 and 5. CPF methodology isapplicable to any inorganic powder and organometallic powders withelectrophilic or nucleophilic ligands. The CPF procedure can use lowcost raw materials as the starting raw materials and if needed,additional purification or separation can be done in-situ. Inert oroxidative atmospheric conditions required for powder synthesis areeasily achieved with the equipment for this method. Temperatures for thereactions forming the complexcelle are ambient or slightly warm butpreferably not more than 100° C. The CPF process can be a batch processor a continuous process wherein product is moved from one piece ofequipment to the next in sequence. A comparison of traditional methodsand other conventional processing is diagrammed in FIG. 2 with this CPFmethodology. Representative examples are discussed and compared withcommercially available samples showing both physical properties andperformance improvements of powders synthesized using this CPFmethodology.

The CPF method produces fine, ultrafine and nanosize powders in a simpleefficient way by integrating chemical principles of crystallization,solubility, transition complex formation, phase chemistry, acidity andbasicity, aqueous chemistry, thermodynamics and surface chemistry.

It is preferred to produce these powders with the selected properties atthe onset of the contact among the elements as these are combined tomake the desired compound. The time when crystallization begins and, inparticular, when the nucleation step begins, is the most crucial stageof formation of nanosize powders. A particular advantage provided by CPFis the ability to prepare the nanosize particles at the onset of thisnucleation step. The solute molecules from the starting reactants aredispersed in a given solvent and are in solution. At this instance,clusters begin to form on the nanometer scale on the bubble surfaceunder the right conditions of temperature, supersaturation, and otherconditions. These clusters constitute the nuclei wherein the atoms beginto arrange themselves in a defined and periodic manner which laterdefines the crystal microstructure. Crystal size and shape aremacroscopic properties of the crystal resulting from the internalcrystal structure.

After the nucleation begins, crystal growth also starts and bothnucleation and crystal growth may occur simultaneously as long assupersaturation exists. The rate of nucleation and growth is determinedby the existing supersaturation in the solution and either nucleation orgrowth occurs over the other depending on the supersaturation state. Itis critical to define the concentrations of the reactants requiredaccordingly in order to tailor the crystal size and shape. If nucleationdominates over growth, finer crystal size will be obtained. Thenucleation step is a very critical step and the conditions of thereactions at this initial step define the crystal obtained. Bydefinition, nucleation is an initial phase change in a small area suchas crystal forming from a liquid solution. It is a consequence of rapidlocal fluctuations on a molecular scale in a homogeneous phase that isin a state of metastable equilibrium. Total nucleation is the sum effectof two categories of nucleation—primary and secondary. In primarynucleation, crystals are formed where no crystals are present asinitiators. Secondary nucleation occurs when crystals are present tostart the nucleation process. It is this consideration of thesignificance of the initial nucleation step that forms the basis forthis CPF methodology.

In the CPF methodology, the reactants are dissolved in a solutionpreferably at ambient temperature or if needed, at a slightly elevatedtemperature but preferably not more than 100° C. Selection ofinexpensive raw materials and the proper solvent are important aspectsof this invention. The purity of the starting materials are alsoimportant since this will affect the purity of the final product whichmay need specified purity levels required for its performancespecifications. As such, low cost starting materials which can bepurified during the preparation process without significantly increasingthe cost of processing must be taken into consideration. For instance,if a preferred starting raw material is a carbonate salt, one can startwith a chloride salt as most reactants from rock processing are chloridesalts. There may be some impurities in this chloride salt that may needto be removed and depending on the ease of impurity reduction, thischloride salt can be converted to the carbonate salt and at the sametime remove any impurity or reduce the impurity levels.

CPF uses conventional equipment in an innovative way to produce thenanosize nuclei required for the final product. CPF utilizes a reactorfitted with a gas diffuser to introduce gas into the solution therebycreating bubbles. An agitator vigorously disperses the solutionsimultaneously with the bubble formation, as the second reactant isintroduced into the first solution. The combination of gas flow andagitation provides a bubble surface. The bubble surface serves as theinterface of contact between the molecules of the first solution and themolecules of the second solution thereby providing a surface reaction.

A surface reaction is the adsorption of one or more reactants from agas, liquid or dissolved solid on a surface. Adsorption may be aphysical or chemical adsorption.

The CPF process creates a film of the adsorbate on the bubble surface ofthe adsorbent. The bubble surface is the adsorbent and the adsorbatesare the reactants in the solution. As illustrated in FIG. 6A, a bubble,61, with a bubble surface, 62, shown above the bulk of the solution, 68.is formed from solution due to the simultaneous introduction of gas andagitator speed. Different size bubbles can be formed depending on gasflow rates. The size of the bubbles defines the surface area of contactbetween the molecules and this relates to the degree of nucleation whichinfluences the particle size.

In FIG. 6B, the top view of this complexcelle is shown schematically.The complexcelle comprises gas bubble, 61, with a bubble surface, 62.The first reactant cation, 63, the first reactant anion, 64, the secondreactant cation, 65 and the second reactant anion, 66, are all on thebubble surface.

Solvent is not illustrated in the schematic diagram but it is understoodthat the solvent molecules are present. In FIG. 7, an illustration ofthis surface pathway is diagrammed showing the start of bubbleformation, 61, from the bulk of the solution, the surface nucleation onthe bubble surface, 62, which forms the complexcelle having reactantions, 63-66, and the separation of this complexcelle from the bulk, 68,of the solution. The water molecules, 67, or solvent molecules areshown. This is a very dynamic state as the solution is vigorously andcontinuously mixed during the time of the addition of the secondreactant solution into the first reactant solution. Furthermore, bubblesare formed within the bulk of the solution and the general direction isfor these bubbles to move towards the top surface of the solution. Theagitation rate enhances the rise of these bubbles to the surface andmixes the solution vigorously so that there is significant turnover ofthese reactants and their bubbles allowing fresh surface bubbles tocontinually be available for complexcelle formation. It will be realizedthat the above mechanism is a postulated mechanism and the presentinvention should not be construed as being limited to this particularpathway.

It is preferred that the gas be introduced directly into the solutionwithout limit to the method of introduction. The gas can be introducedinto the solution within the reactor by having several gas diffusers,such as tubes, located on the side of the reactor, wherein the tubeshave holes for the exit of the gas as illustrated in FIG. 4. Anotherconfiguration is to have a double wall reactor such that the gas passesthrough the interior wall of the reactor. The bottom of the reactor canalso have entry ports for the gas. The gas can also be introducedthrough the agitator shaft, creating the bubbles upon exiting. Severalother configurations are possible and the descriptions of thesearrangements given herein are not limited to these. Throughout thedescription the point of gas being introduced into the liquid is a gasdiffuser.

In one embodiment an aerator can be used as a gas diffuser. Gasdiffusing aerators can be incorporated into the reactor. Ceramicdiffusing aerators which are either tube or dome-shaped are particularlysuitable for demonstration of the invention. The pore structures ofceramic bubble diffusers produce relatively fine small bubbles resultingin an extremely high gas to liquid interface per cubic feet per minute(cfm) of gas supplied. This ratio of high gas to liquid interfacecoupled with an increase in contact time due to the slower rate of thefine bubbles accounts for the higher transfer rates. The porosity of theceramic is a key factor in the formation of the bubble and significantlycontributes to the nucleation process. While not limited thereto formost configurations a gas flow rate of at least one liter of gas perliter of solution per minute is suitable for demonstration of theinvention.

A ceramic tube gas diffuser on the sides of the reactor wall isparticularly suitable for demonstration of the invention. Several ofthese tubes may be placed in positions, preferably equidistant from eachother, to create bubbling more uniformly throughout the reactor. The gasis preferably introduced into the diffuser within the reactor through afitting connected to the header assembly which slightly pressurizes thechamber of the tube. As the gas permeates through the ceramic diffuserbody, fine bubbles start being formed by the porous structure of thematerial and the surface tension of the liquid on the exterior of theceramic tube. Once the surface tension is overcome, a minute bubble isformed. This small bubble then rises through the liquid forming aninterface for transfer between gas and liquid before reaching thesurface of the liquid level.

A dome-shaped diffuser can be placed at the bottom of the reactor or onthe sides of the reactor. With dome shape diffusers a plume of gasbubbles is created which is constantly rising to the surface from thebottom providing a large reactive surface.

A membrane diffuser which closes when gas flow is not enough to overcomethe surface tension is suitable for demonstration of the invention. Thisis useful to prevent any product powder from being lost into thediffuser.

In order to have higher gas efficiencies and utilization, it ispreferred to reduce the gas flow and pressure and expend less pumpingenergy. A diffuser can be configured such that for the same volume ofgas, smaller bubbles are formed with higher surface area than if fewerlarger bubbles are formed. The larger surface area means that the gasdissolves faster in the liquid. This is advantageous in solutionswherein the gas is also used to solubilize the reactant by increasingits solubility in the solution.

Smaller bubbles also rise more slowly than the larger bubbles. This isdue to the friction, or surface tension, between the gas and the liquid.If these bubbles start from the same position or depth in the reactor,the larger bubbles reach the surface more quickly than several smallerbubbles. The smaller bubbles will have more liquid as it rises. Thebubble surface interface between the two reactants determines thenucleation rate and size can therefore be tailored by controlling thebubble size formation.

Nozzles, preferably one way nozzles, can be used to introduce gas intothe solution reactor. The gas can be delivered using a pump and the flowrate should be controlled such that the desired bubbles and bubble ratesare achieved. A jet nozzle diffuser, preferably on at least one of thesides or bottom of the reactor, is suitable for demonstration of theinvention.

The rate of gas introduction is preferably sufficient to increase thevolume of the solution by at least 5% excluding the action of theagitator. In most circumstances at least about one liter of gas perliter of solution per minute is sufficient to achieve adequate bubbleformation. It is preferable to recycle the gas back into the reactor.

Transfer of the second reactant solution into the first reactor solutionis preferably done using a tube attached to a pump connecting thesolution to be transferred to the reactor. The tube into the reactor ispreferably a tube with a single orifice or several orifices of a chosenpredetermined internal diameter such that the diameter size can delivera stream of the second solution at a given rate. Atomizers with finenozzles are suitable for delivering the second solution into thereactor. The tip of this transfer tube can comprise a showerhead therebyproviding several streams of the second solution reacting on severalsurface bubbles simultaneously. Nucleation is influenced not only by theconcentration of the second solution but also by the instantaneousconcentration of this solution as it reaches the surface bubbleinterface to form the complexcelle. In large scale production, the rateof transfer is a time factor so the transfer rate should be sufficientlyrapid enough to produce the right size desired.

The agitator can be equipped with several propellers of differentconfigurations, each set comprising one or more propellers placed at anangle to each other or on the same plane. Furthermore, the mixer mayhave one or more sets of these propellers. The objective is to createenough turbulence for rapid bubble formation and turnover. Examples ofthe agitator arrangements are shown in FIG. 5 A-G but other similarformations are also possible and not limited to these. The function ofthis mixer is not only to insure homogeneity of the reaction mixture butalso to assist in the bubble surface interaction which furtherinfluences the nucleation and is a determining factor in the size of thefinal particle.

Straight paddles or angled paddles are suitable. The dimensions anddesigns of these paddles determine the type of flow of the solution andthe direction of the flow. One preferred blade design for CPFmethodology is shown in FIG. 5 where the paddles consist of concentricrings wired around the paddle that create a frothing effect in thesolution. In addition, the paddle can rotate on its own axis as well asrotate vertically by the axis of the mixer. This maximizes the bubblingeffect even under slower agitation speed. A speed of at least about 100rotations per minute (rpm's) is suitable for demonstration of theinvention.

The CPF process steps are demonstrated in the following examples belowfor a desired final product M_(j)X_(p) such that M=M₁ M₂ M₃ (dual metalcation) or more and X_(p)=O. The flow chart in FIG. 3 shows a schematicoutlay of the application of the CPF methodology to powders M_(j)X_(p)as defined earlier for two reactants. It is obvious to someone skilledin the art that some modifications of these process steps would be donedepending on the starting reactants, the desired precursor and the finaldesired product.

The starting raw materials for this process are chosen from Groups IA,IIA, IIIA, IVA and transition metals with the anion being monatomic or apolyanion selected from Groups IIIA, IVA, VA, VIA and VIIA. The finalpowders are cation compounds of anions or polyanions such that theformula is M_(j)X_(p) where M_(j) may be a single cation or a mixture ofmetal cations and X_(p) may be a single anion, a single polyanion or amixture of mixed anions and polyanions. M_(j) may be M₁ M₂ M₃ or morewhich are in stoichiometric or non-stoichiometric ratios and one or twomay be small dopant amounts not more than 10 weight % of the finalpowder. The anion and polyanions may be oxides, carbonates, silicates,phosphates, borates, aluminates, silicophosphates, stannates,hydroxides, nitrates, oxycarbonates, hydroxycarbonates, fluorides, andoxyfluorides without limited thereto. Examples of these desired highperformance powders are utilized in lithium ion battery applications,rechargeable batteries, bone implants, dental implants, structuralceramics, optical communication fibers, medical patches for drugdelivery and specialized composites of metal-metal, metal-ceramic,glass-ceramic, glass-metal and others but not limited to these. Thefollowing discussion will illustrate the complexometric precursorformulation technology as applied to the synthesis of a lithium cathodematerial for lithium ion batteries. It is known that this art is notlimited to this illustrative example but is applicable to numerousspecialized high performance powders which are very expensive tomanufacture today. The reactants in each solution are preferably no morethan 30 wt. % of the solution.

A first reactant solution A is prepared by dissolving the solid in aselected solvent, preferably a polar solvent such as water but notlimited thereto. It is understood that the choice of solvent depends onthe type of final powder product desired, the formulated composition ofthe final powder and the physical characteristics required for achievingthe performance of the final powder. The choice of the solvent isdetermined by the solubility of the solid reactant A in the solvent andthe temperature of dissolution. It is preferred to dissolve at ambienttemperature and to dissolve at a fast rate so that solubilization is notenergy intensive. The dissolution may be carried out at a slightlyhigher temperature but preferably below 100° C. Only if otherdissolution methods fail should a higher temperature be used. Otherdissolution aids may be addition of an acid or a base. The solutionconcentration is preferably low as this influences concentration at thesurface bubble interphase during the nucleation which determines thefinal powder size. It is important to select the proper chemicalenvironment in order to produce the right nucleation to yield thedesired final powder characteristics.

The cost of the starting materials should also be considered in the sumtotal of the process cost. Generally, lower cost raw materials are thesalts of chlorides, nitrates, hydroxides and carbonates. Acetate saltsand other compounds are usually prepared from these so these downstreamcompounds will be at higher cost. Nitrates and sulfates are readilysoluble in water but they also release noxious gases during hightemperature calcination. The purity of the starting materials is also acost consideration and technical grade materials should be the firstchoice and additional inexpensive purification should be factored in theselection of the starting materials.

A second reactant solution B is also prepared in the same way asreactant solution A. The solid starting material and the solventselected for dissolution should yield the fastest dissolution under mildconditions as possible.

The reactor, 1, set-up for both solutions A and B is diagrammed in FIG.4. Baffles, 2, are preferred and are preferably spaced at equal distancefrom each other. These baffles promote more efficient mixing and preventbuild-up of solid slags on the walls of the reactor. A top cover, 5, islatched to the bottom section of the vessel using a flange or bolts, 4.An O-ring, 3, serves to seal the top and bottom sections of the reactor.The mixer shaft, 7, and the propeller, 8-9, are shown in FIG. 4 and inmore detail in FIG. 5. The mixer shaft is preferably in the center ofthe reactor vessel and held in place with an adaptor or sleeve, 6. Gasis introduced through a gas diffuser such as gas tubes, 10, which havesmall outlets on the tube for exit of the gas. These gas tubes areplaced vertically into the reactor through the portholes of the topcover and held in place with adaptors, 6. The gas used for bubbling ispreferably air unless the reactant solutions are air-sensitive. In thisinstance, inert gas is employed such as argon, nitrogen and the like.Carbon dioxide is also used if a reducing atmosphere is required and itcan also be used as a dissolution agent or as a pH adjusting agent.Ammonia may also be introduced as a gas if this is preferable to use ofan ammonia solution. Ammonia can form ammonia complexes with transitionmetals and a way to dissolve such solids. Other gases such as SF₆, HF,HCl, NH₃, methane, ethane or propane may also be used. Mixtures of gasesmay be employed such as 10% O₂ in argon as an example. Another portholeon the top cover of the reactor is for the transfer tube (not shown) andanother porthole can be used for extracting samples, adding otherreactant, as Reactant C for pH adjustment or other, and also ormeasurements of pH or other needed measurements.

The agitator blade illustrated in FIG. 5 with a concentric wire designis preferred over the regular paddle type since this assists in bubbleformation and allows the solution system to be in a dynamic motion suchthat fresh bubble surfaces are continuously and rapidly produced as thesecond solution of reactant B is being transferred into the reactorcontaining solution of reactant A. The agitator blade has concentricwire wound, 9, and it can rotate on its axis, 10, as shown in a top viewin FIG. 5A. A side view of this design is shown in FIG. 5B. FIGS. 5C-5Gillustrate different arrangements of blades. The concentrically woundwires are not shown to simplify the diagrams. The blade is attached tothe mixer shaft (7) as shown in FIG. 5C and one set of propellers withthree blades rotate horizontally on their own axes (FIGS. 5C-10) andalso rotate vertically (FIGS. 5C-11) simultaneously on the mixer shaftaxis, 11. In FIG. 5D, two sets of propellers with three blades each aredrawn which move as in FIG. 5C. There are three blades arrangedalternately on the mixer shaft in FIG. 5E. In FIG. 5F, the arrangementis similar to FIG. 5C but there are two sets of propellers with fourblades. In FIG. 5G, the four blades are arranged one above the other onthe mixer shaft as in FIG. 5C. There can be many variations of theseconfigurations with different number of blades, different bladedimensions, different plurality of blades in a set, several sets ofblades, different angular orientation relative to each other, differentnumber of coils per blade, etc. The blade configurations are not limitedto these illustrations in FIG. 5.

The rate of transfer has a kinetic effect on the rate of nucleation. Apreferred method is to have a fine transfer stream to control theconcentration of the reactants at the bubble surface interface whichinfluences the complexcelle formation and the rate of nucleation overthe rate of crystal growth. For smaller size powder, a slower transferrate will yield finer powders. The right conditions of the competingnucleation and growth must be determined by the final powdercharacteristics desired. The temperature of reaction is preferablyambient or under mild temperatures if needed.

Upon completion of the reaction of reactant A and reactant B, theresulting slurry mixture containing the intermediate complexcelle isdried to remove the solvent and to obtain the dried powder. Any type ofdrying method and equipment can be used and such drying is preferably atless than 350° C. Drying can be done using an evaporator such that theslurry mixture is placed in a tray and the solvent is released as thetemperature is increased. Any evaporator in industrial use can beemployed. The preferred method of drying is by using a spray dryer witha fluidized nozzle or a rotary atomizer. These nozzles should be thesmallest size diameter although the size of the powder in the slurrymixture has already been predetermined by the reaction conditions. Thedrying medium is preferably air unless the product is air-sensitive. Thespray dryer column should also be designed such that the desiredmoisture content is obtained in the sprayed particulates and are easilyseparated and collected.

The spray dried particles obtained by the CPF methodology are very fineand nanosize. Definitive microstructures or nanostructures by the CPFprocess are already formed during the mixing step. Novel microstructuresor nanostructures looking like flowers or special layering such thatthese structures are called nanorose, nanohydrangea, or nanocroissant orother description depending on the formulation of the powder. Suchstructures also translate to the final powder after the calcinationstep.

After spray drying, the powder is transferred to a calciner. No crushingor milling is required since the spray dried powders are very fine. Inlarge scale production, this transfer may be continuous or batch. Amodification of the spray dryer collector such that an outlet valveopens and closes as the spray powder is transferred to the calciner canbe implemented. Batchwise, the spray dried powder in the collector canbe transferred into trays or saggers and moved into a calciner like abox furnace although protection from powder dust should also beimplemented. A rotary calciner is also another way of firing the powder.A fluidized bed calciner is also another way of higher temperature heattreatment of the spray dried powder. The calcination temperature isdetermined by the composition of the powder and the final phase puritydesired. For most oxide type powders, the calcination temperatures rangefrom as low as 400° C. to slightly higher than 1000° C. Aftercalcination, the powders are crushed as these are soft and not sintered.The CPF process delivers non-sintered material that does not requirelong milling times nor does the final CPF process require classifiers toobtain narrow particle size distribution. The particle sizes achievableby the CPF methodology are of nanosize primary and secondary particlesand up to small micron size secondary particles ranging to less than 50micron aggregates which are very easily crushed to smaller size. Itshould be known that the composition of the final powder influences themorphology as well.

A brief stepwise summary of the CPF methodology is given below.

A first solution or slurry solution of M=M₁ chosen from the metalchlorides, metal nitrates, metal hydroxides, metal acetates, metalcarbonates, metal hydroxycarbonates, metal hydroxyl phosphates and metalhydroxysilicates but not limited to these would be prepared. The purityof the starting reactant for M₁ should be defined by the final puritydesired and the degree of purification that may be done in a preliminarystep.

A second solution or slurry solution of M=M₂ also chosen from the samemetal salts as for the first solution. The purity of the startingreactant for M₂ should also be chosen on the basis of the final purityof the final product and the degree of purification needed in apreliminary step.

The solvent in both the first and second solution is preferablydeionized water at acidic or basic pH and ambient temperature. An acidor a base may be added to the first or second solution to aid insolubilizing the reactants and/or the temperature may be increased butpreferably not more than 100° C., and/or the solubilizing mixing rate bemore vigorous and solubilizing time increased. If conditions requiremore adverse temperature and time, then the process may proceed asslurry solutions. Other solvents to dissolve the starting materials mayalso be used if water is insufficient for dissolution. Such solvents maybe polar solvents as alcohols or non-polar solvents typically used ingeneral organic preparations. It is important to consider raw materialcosts during the evaluation of the process so that production cost doesnot decrease the value-added performance advantages of the CPF powder.

A CPF reactor designed or configured so that gas may be introduced intothe vessel is charged with the first solution. The gas may be air,argon, carbon dioxide, nitrogen, or mixtures of these preferably ofnormal purity. The gas may be inert for reactions that are adverse inair. Likewise, the gas may also be a possible reactant such as, forexample, those reactions wherein carbon dioxide is utilized to producecarbonates or bicarbonates, or hydroxycarbonates and oxycarbonates butnot limited to these.

The gas may be introduced by a gas diffuser such as gas tubes havingholes in the tube from which the gas introduced from the inlet exitsinto the reactor vessel creating a vigorous flow and a bubbling solutionwith numerous fine micro-bubbles. The holes may be sized to insurebubbles are generated over the entire length of the tube.

The gas may also be introduced by mechanical gas diffusers with pumpsthat may circulate both gas and solution which also improves mixing ofthe solutions.

The gas flow rate, in conjunction with the mixing speed of the agitator,should be enough to create suspended micro bubbles such as a foamysolution.

An agitator blade is configured to produce vigorous mixing to produce afrothy slurry solution or frothy solution. The agitator blade may be aconcentric loop to promote incorporation of the gas and the formation offine bubbles. The concentric loop may rotate horizontally andvertically. In addition, the agitator blade may be dual, triple,quadruple, quintuple or other configuration and not limited to these.Depending on the height of the reactor vessel, several agitator bladesmay be used.

The mixing speed should be fast enough to maintain bubbles of firstsolution such that the second solution being added drops into thebubbles of the first solution creating a micro or nano contact onto thesurface of the bubbles of the second solution.

The first solution may be added to the second solution. The resultingproduct performance may be different depending on the method ofaddition.

The mixing temperature is preferably ambient or slightly elevated butnot more than 100° C.

The resulting mixture of first and second solutions may be a solution ora slurry mixture.

The resulting reaction product is dried by any drying method using knownindustrial equipment including spray dryers, tray dryers, freeze dryersand the like, chosen depending on the final product preferred. Thedrying temperatures would be defined and limited by the equipmentutilized. The desired drying temperatures are usually from 200-325° C.

The resulting mixture is continuously agitated as it is pumped into thespray dryer head if spray dryers, freeze dryers or the like are used.For tray dryers, the liquid evaporates from the surface of the solution.

The dried powders are transferred into the next heating systembatch-wise or by means of a conveyor belt. The second heating system maybe a box furnace utilizing ceramic trays or saggers as containers, arotary calciner, a fluidized bed, which may be co-current orcounter-current, a rotary tube furnace and other similar equipment butnot limited to these. The calcination temperature depends on the finalproduct requirements and could be as high as 1000° C. and up to as muchas 3000° C. or more as in the case of glassy silicates.

The heating rate and cooling rate during calcinations depend on the typeof final product desired. Generally, a heating rate of about 10° C. perminute is preferred but the usual industrial heating rates are alsoapplicable.

Calcining may also require inert gases as in the case of those materialsthat are sensitive to oxidation. As such, a positive flow of the inertgas may be introduced into the calcining equipment.

The final powder obtained after the calcining step is a fine, ultrafineor nanosize powder that does not require additional grinding or millingas is currently done in conventional processing. Particles arerelatively soft and not sintered as in conventional processing.

The final powder is preferably characterized for surface area, particlesize by electron microscopy, porosity, chemical analyses of the elementsand also the performance tests required by the preferred specializedapplication.

The CPF methodology for the production of fine, ultrafine and nanosizepowders offers several advantages. One of the improvements is reductionin the number of processing steps. There is no significant milling andfiring sequence in the CPF method. The total production time for thisCPF methodology route to fine, ultrafine and nanosize powders is lessthan or equal to 25% of current conventional processing technologies forsuch similar powders. Final powder production cost using CPF methodologycan be significantly reduced by as much as 75-80% of currentconventional processing. Performance improvements of these powdersproduced by CPF are at least 15% or more than those traditional ceramicpowders currently produced by presently known technologies. The CPFprocess can be utilized for the preparation of different types ofpowders and is not limited to a group of powder formulations.

This CPF process can be applied to make the desired powder for thelithium ion batteries, such as lithium cobalt oxide, lithium nickeloxide, lithium manganese oxide and the doped lithium metal oxides ofthis type, the mixed lithium metal oxides of said metals and the dopedderivatives, lithium iron phosphate and the doped lithium ironphosphates as well as other lithium metal phosphates, lithium titanatesand other materials for the storage batteries. The CPF process can beapplied to produce medical powders such as the specialized calciumphosphates for medical applications like bone implants. The CPF processcan also be used for the preparation of other advanced ceramic powderssuch as lithium niobates and lithium tantalates, lithium silicates,lithium aluminosilicates, lithium silicophosphates and the like.Semiconductor materials can also be prepared by the CPF process as wellas specialized pharmaceutical drugs. High surface area catalysts can bemade by the CPF process and such catalysts would have higher catalyticactivity as a result of a finer particle size, higher surface area andhigher porosity made possible by the CPF methodology. Specializedcoatings requiring nanosize powders can be economically prepared by theCPF method. This CPF process can also be used for the preparation ofnon-lithium based materials. The versatility of this methodology allowsitself to be easily modified in order to achieve the customized,tailored powder needed. Furthermore, this methodology is easily adaptedfor large scale industrial production of specialized powders requiring anarrow particle size distribution and definitive microstructures ornanostructures within the fine, ultrafine or nanosize powders. Having acost effective industrial scale powder for these specializedapplications will allow commercial development of other devicesotherwise too costly to manufacture.

The complexometric precursor formulation methodology or CPF, creates afine, ultrafine or nanosize powders via the formation of a complexcelleof all the ions of the desired powder composition on a bubble surfaceinterface. CPF has many advantages over known prior art.

Only the main reactants for the chemical formula of the compound to besynthesized are used. This will reduce the cost of the raw materials.The starting raw materials can be low cost. Technical grade materialscan be used and if needed, purification can be done in-situ.

Total processing time is significantly less, about ⅕ to ½ of theprocessing times for the present industrial processes.

Special nanostructures are preformed from the complexcelle which arecarried over to the final product thus enhancing the performance of thematerial in the desired application. For the purposes of the presentinvention nanostructures are defined as structures having an averagesize of 100 to 300 nm primary particles.

Neither surfactants nor emulsifiers are used. The initiation reactionoccurs at the surface of the bubble interface. In fact, it is preferablethat surfactants and emulsifiers are not used since they may inhibitdrying.

Size control can be done by the size of the bubbles, concentration ofthe solutions, flow rate of the gas, transfer rate of second reactantinto the first reactant.

No repetitive and cumbersome milling and classification steps are used.

Reduced calcination time can be achieved and repetitive calcinations aretypically not required.

Reaction temperature is ambient. If need for solubilization, temperatureis increased but preferably not more than 100° C.

Tailored physical properties of the powder such as surface area,porosity, tap density, and particle size can be carefully controlled byselecting the reaction conditions and the starting materials.

The process is easily scalable for large scale manufacturing usingpresently available equipment and/or innovations of the presentindustrial equipment.

EXAMPLES

Preparation of Coin Cells

The standard practice for coin cell testing has been used in all exampleand is described herein for reference. The material was made intoelectrodes in the same way and tested in an Arbin battery cycler(BT-2000) under the same cycling conditions of voltage and current. Assuch, side-by-side comparison of the battery cycling performancesdefinitively exemplifies the advantages of the CPF methodology overcurrent industrial production processes.

Electrodes were prepared by mixing 80 wt. % of active material, 10 wt. %of carbon black, and 10 wt. % PVDF (polyvinylideneflouride) in NMP(1-methyl-2-pyrrolidone). The resulting slurry was cast on aluminum foiland dried in a vacuum oven at 115° C. for 24 h. CR2032-type coin cellswere fabricated in an argon-filled glove box using lithium metal as thecounter electrode. The cathode weight was around 4 mg per electrode. Theelectrolyte was a 1 M solution of LiPF₆ (lithium hexafluorophosphate) ina 1:1:1 volume mixture of EC:DMC:DEC (ethylene carbonate, dimethylcarbonate, and diethyl carbonate). The separator (Celgard 2400) wassoaked in the electrolyte for 24 h prior to battery testing. Coin-cellswere galvanostatically charged/discharged on the Arbin battery cycler atthe stipulated current densities. Tests were done at ambienttemperature. Both comparative example and the example coin cells weredone at the same time under the same conditions.

EXAMPLES Comparative Example 1

Commercially available lithium cobalt oxide powder was obtained fromSigma Aldrich and characterized by field emission SEM (FIGS. 8A and 8B)and XRD (FIG. 9) as well as by coin cell testing.

The scanning electron micrograph of this commercial LiCoO₂ in FIG. 8Ahas a magnification of 2000× and was taken as received. A secondmicrograph in FIG. 8B has a magnification of 25000×. In FIG. 8A, theparticles are acicular and have several large agglomerates more than 10microns that fused together during the calcination stage. On highermagnification, layers of the particles are noted for some particles thatwere not fused but it is also shown that there are smooth areas fromfusion of particles. This is often found in solid state processes whichare a calcination of blended mixed solids of the reactants that combineby sintering at high temperature. It is expected that the particles soderived would be large in size and will need to be milled and classifiedto obtain the size distribution preferred.

The X-ray powder diffraction in FIG. 9 shows a single phase crystallineLiCoO₂.

The capacity of this lithium cobalt oxide prepared commercially is shownin FIG. 14 together with Example 2 prepared by CPF.

Example 2

Lithium cobalt oxide was prepared using a reactor vessel as shown inFIG. 4 with a mixer having an agitator blade as shown in FIG. 5. In onereactor, a weighed amount of lithium carbonate (46.2 grams, 99% purity)was added to the reactor containing one liter of deionized water. Carbondioxide gas was allowed to flow through the reactor using a gas tubebubbler on the side or a diffuser bubbler at the bottom of the vessel. Asecond reactor also equipped with a tube bubbler or a diffuser bubblercontained a weighed amount of cobalt carbonate (120.2 grams, 99% purity)and one liter of deionized water. Carbon dioxide gas was allowed to flowthrough the bubblers. Ammonia, 250 mL, was added to the second reactor.After a given amount of time to allow dissolution or vigorous mixing ofthe corresponding reactants, the cobalt solution was pumped into thelithium solution at a rate of at least 1 L/h. Reaction temperature wasambient and gas flow maintained a sufficient amount of bubbles. Theresulting mixture was passed through a spray dryer. The outlettemperature was 115° C. The dried powder was collected and placed in asagger and fired in a box furnace in air for 5 h at 900° C. Scanningelectron micrographs (FIGS. 10-12) and X-ray powder diffraction patterns(FIG. 13) were taken of the dried powder and the fired powder.

The slurry after mixing the reactants was placed on a glass surface todry in air. The air-dried powder was analyzed by field emission SEM andthe micrograph is shown in FIG. 10. It is shown that there is somenanostructure already formed from the CPF methodology. The particlesappear to align as staggered layers. Primary particles are in thenanometer range as shown by several individual particles interspersedwithin.

In FIG. 11A (10000×) and 11B (25000×), the same nanostructure can beseen after spray drying the slurry mixture from the mixing step. Thelayering structure is very clearly shown in FIG. 11B. That thenanostructure still remains after drying indicates that this formationis an advantage of the CPF process.

After the calcination step for 5 h at 900° C., the layered nanostructureobserved in FIGS. 10 and 11 still remains intact in the calcined powderas shown in the SEM micrograph in FIG. 12 at 10000× which consists ofloosely bound layers of the particles allowing ease of Li migrationwithin the structure during battery cycling. Such flaky structureresembles a “nanocroissant” and has already been formed from theprecursor feed to the spray dryer and thereon to the calciner.

Coin cells were prepared as described in the preparation of coin cells.The capacity of this lithium cobalt oxide prepared by the CPFmethodology is shown in FIG. 14 plotted with the commercial sample inExample 1 for 500 cycles at C/20. From the data, the commercial sampleof Example 1 performed lower, as shown by the lower discharge capacity.Both powders decreased in capacity with increase in the number ofcycles. However, the powder prepared by the CPF process exhibited highercapacity up to 400 cycles compared to the commercial sample ofExample 1. At 300 cycles, the capacity of the CPF powder of Example 2was 110 mAh/g compared against the capacity of the commercial sample at300 cycles which was 80 mAh/g.

Example 3

The powders in Examples 1 and 2 were refired at 900° C. for another 5 h.Coin cells were prepared as described. A comparison of the batterycycling tests is given in FIG. 15 at 1 C for 500 cycles.

In the battery cycling tests at a higher C rate of 1 C, the lithiumcobalt oxide powder from Example 2 that was refired again performedsignificantly better than the commercial powder that was also refired atthe same temperature and for the same time period. The capacity of thecommercial sample dropped from 120 mAh/g to 20 mAh/g after 200 cycles.The CPF sample had a capacity of 100 mAh/g after 300 cycles and 80 mAh/gat 400 cycles.

The present invention provides a cathode for a battery wherein thebattery has a capacity of at least 80 mAh/g after 200 cycles

The scanning electron micrographs of the refired samples are shown inFIGS. 16 and 17 at the same magnification of 10000× for comparison.While recalcination for another 5 h has caused more fusion in bothsamples, it is noted that the commercial sample of lithium cobalt oxidehas larger fused particles and the layers were also more fused together.The lithium cobalt sample prepared by this invention still retained muchof the layered structure and the additional firing has not diminishedbattery performance significantly compared to the commercial sample.

Example 4

The same procedure described in Example 2 was used in this example butwith the added nickel and manganese compounds to illustrate thesynthesis of multicomponent lithium oxides by the CPF methodology. Theformulation made is Li_(1.20)Ni_(0.18)Mn_(0.50)Co_(0.12)O₂ which is ahigh energy lithium nickel manganese cobalt oxide material for lithiumion batteries that would meet the electric vehicle performancestandards.

Nickel hydroxide (16.8 grams, 99%) and cobalt carbonate (14.4 grams,99.5%) were weighed out and placed in a reactor vessel described in FIG.4 equipped with a tube bubbler and an agitator as shown in FIG. 5already containing one liter of deionized water and 140 mL of aceticacid (99.7%). The solids were mixed at ambient temperature to obtain asolution of both metals. Manganese acetate (123.3 grams) was thenweighed out and added to the same reactor. A similar reactor was alsoset-up to contain one liter of deionized water and lithium carbonate(44.7 grams, 99%). Carbon dioxide was bubbled through the gas bubbler.Ammonia, 100 mL, was added to the Li-containing reactor. The Co, Ni, Mnsolution was then pumped into the Li-containing reactor at about 3.5 L/hat ambient temperature. Additional ammonia, 155 mL, was then added tothe mixture to maintain pH of at least 9.0. The resulting mixture wasthen dried in a spray dryer. Inlet temperature was at 115° C. TheLi—Co—Ni—Mn spray dried powder was then placed in a sagger and calcinedat 900° C. for 5 h. The fired powder was very soft and was just crushed.No classification was done.

Scanning electron micrographs (FIGS. 18-20) and X-ray powder diffractionpatterns (FIG. 21) were taken of the dried powder and the fired powder.Note that the SEM data in FIGS. 18A (2000×) and 18B (10000×) beforespray drying and FIGS. 19A (5000×) and 19B (10000×) after spray dryingshow a “nanorose” or a “nanohydrangea” structure as the nanostructuresformed by the layering of the particles look similar to these flowers.The particles form nanostructure layers at the mixing stage where thecomplexcelle nucleation begins and this same nanostructure is retainedeven after spray-drying. The calcined powder has discrete nanoparticlesabout 200-300 nm and some very loose agglomerates as shown in the SEMmicrographs in FIGS. 20A (10000×) and 20B (25000×).

A crystalline lithium nickel manganese cobalt oxide was obtained in theX-ray powder diffraction pattern in FIG. 21.

Coin cells were prepared as described in Example 1. The capacity of thislithium nickel cobalt manganese oxide prepared by the CPF methodology isshown in FIGS. 22-24.

In FIG. 22, the capacity of this lithium nickel manganese oxide wasrelatively constant at an average of 125 mAh/g for 500 cycles at a highC rate of 1 C. This is indicative of potential high performance inlithium ion batteries for electric vehicle applications. Capacityretention for as much as 500 cycles at 1 C is excellent performance.

In FIG. 23A, the battery performance for the same material was done in atemperature controlled chamber at 30° C. and plotted showing differentcycling rates from C/20 to 1 C. As shown, the capacity decreases as theC rate increases. At C/20, the capacity was about 250 mAh/g and at 1 C,about 150 mAh/g.

In FIG. 23B, the C rates shown are C/10, C/3 and 1 C for 5 cycles each.Capacities were 240 mAh/g, 180 mAh/g and 150 mAh/g, respectively. Thebattery cycling tests were done at 30° C. in a temperature controlledchamber.

In FIG. 24A, the battery coin cells were placed in the temperaturecontrolled chamber at 25° C. Cycling rates were taken from C/20 to 1 C.The capacity at C/20 was almost 300 mAh/g. At 1 C, the capacity was at180 mAh/g. This is attributed to a better controlled environment. Thecycling data at 1 C for 500 cycles is shown in FIG. 24B. Capacity wasconstant for 500 cycles at 1 C rate at 25° C.

Example 5

A cathode material, LMPO₄, such as LiFePO₄, which is also preferablycoated with carbon to promote conductivity and may be doped or not, canbe made by this CPF methodology. The iron source can be selected fromdivalent salts of iron. The phosphate source can be H₃PO₄, ammoniumphosphates, ammonium dihydrogen phosphates and the like. Iron is eithera +2 or a +3 ion. The Fe⁺² salt is preferred over the Fe⁺³ salt. Thereactions must be done under inert atmosphere to prevent the oxidationof Fe⁺² to Fe⁺³. A reducing atmosphere can also be used to reduce theFe⁺³ to Fe⁺².

To illustrate the preparation of LiFePO₄, an iron salt soluble inaqueous solvents like water is prepared in one reactor. Such salts canbe iron oxalate, iron nitrate and others. Carbon dioxide gas can beintroduced in the solution. Phosphoric acid is also added to thesolution. In a second reactor, a lithium salt such as lithium carbonate,lithium hydroxide and the like is dissolved in water under carbondioxide gas. The iron phosphate solution in reactor 1 is then slowlytransferred into the lithium solution in the second reactor. Ammoniasolution may be introduced simultaneously as the iron solution or at theend of the transfer of the iron solution. The slurry solution is thendried using a spray dryer and the spray dried powder is calcined underinert atmosphere to obtain LiFePO₄. If a dopant is added from selectedmetals, this dopant solution must be dissolved in any reactor. Thecarbon coating can be attained by adding a carbon material to obtain notmore than a 10 wt. % carbon in the product. The coating may comprisealkali or alkaline earth metals, Group III A and IV A and transitionmetals or an organic or another inorganic compound.

The compound M_(j)X_(p) prepared by the complexometric precursorformulation methodology with the coating comprises carbon or acarbon-containing compound

Other types of phosphate compounds such as calcium phosphate may be madein a similar way to obtain a calcium phosphate nanopowder that can beused for bone implants and other medical applications as well as dentalapplications.

Example 6

Lithium cobalt oxide was prepared using a reactor vessel as in FIG. 4with agitator blades as in FIG. 5. Cobalt nitrate hexahydrate, 149.71grams, was weighed into the reactor containing one liter of deionizedwater. Air was bubbled through the solution using fritted gas tubes.Lithium hydroxide monohydrate, 25.86 grams, was dissolved in deionizedwater, 1 L, in a second container then transferred into the cobaltsolution. Ammonia (28%), 125 mL, was added to the mixture. The mixturewas spray dried and calcined at 900° C. for 5 h.

The SEM micrographs in FIGS. 25 and 26 show the particle sizetransitions for the spray dried material to the fired product at 10000×.Primary particles are about 200-300 nm and secondary ones are about 3.5microns. The particles are nanosize to ultrafine size. There is nosignificant sintering observed from micrographs taken after thecalcination step. No classification was done after the calcination step;the fired powder was lightly crushed.

The X-ray powder diffraction pattern in FIG. 27 shows a crystallinelithium cobalt oxide phase.

The coin cell tests in FIG. 28 show a discharge capacity of about 150mAh/g with slight decrease after 50 cycles at ambient temperature at0.05 C rate.

Example 7

Example 2 was repeated. Lithium carbonate (46.6 grams) was weighed anddissolved in 1 L of deionized water under CO₂ gas at ambienttemperature. In another vessel with a liter of deionized water and CO₂,120.6 grams of cobalt carbonate was weighed and 250 mL of ammoniumhydroxide was also added. The second mixture was transferred into thelithium solution in about one hour, spray dried (inlet temperature of220° C.) then calcined for 5 h at 900° C.

The X-ray powder diffraction pattern in FIG. 29 is a crystalline lithiumcobalt oxide.

Particle size of the calcined powder was done by FESEM (field emissionscanning electron microscopy) in FIGS. 30 A-C.

Coin cell test data is given in FIG. 31 for Example 7 and the commercialsample (Sigma Aldrich) done at room temperature for 500 cycles at 1 C.The product prepared by the CPF process is showed a capacity of 100mAh/g at 400 cycles while the commercial sample had a capacity of about70 mAh/g.

Example 8

The calcined product in Example 7 was fired again for another 5 h at900° C. The X-ray powder diffraction pattern is given in FIG. 32 whichis a single phase crystalline lithium cobalt oxide.

The refired LiCoO2 had particle sizes similar to Example 7 which is asingle fire at 5 h at 900° C. The SEM photos in FIG. 33 are atmagnifications 5000×, 10000×, and 25000×.

A comparison of Example 8 against the refired commercial sample inExample 3 is shown in FIG. 34. The battery performance after 250 cyclesdropped to 30 mAh/g capacity for the commercial sample but Example 8exhibited 120 mAh/g at 250 cycles and was 100 mAh/g after 500 cycles.The coin cell conditions were RT at 1 C. These results indicate superioradvantage of the complexcelle formation of the CPF synthetic method overa similar product prepared by traditional methods.

Example 9

The reactants in Example 7 can be prepared in the same manner. Anothercompound such as aluminum oxide or aluminum fluoride can be added to thesecond solution already containing cobalt as a dopant. The amount ofthis dopant compound depends on the preferred dopant concentration forenhanced performance but is usually less than 10% by weight of the totalcomposition. In some cases, more than one dopant is added depending onthe desired improvement in performance in the presence of the dopant.One of these is improvement in battery cycling results such as longercycle life and higher stable capacity.

Dopant starting materials are usually salts of oxides, hydroxides,carbonates favorably over the nitrates, sulfates, acetates and the like.Among those already used by other researchers are alkaline metals andtransition metals such as Al, Ti, Zr, Mg, Ca, Sr, Ba, Mg, Cr, Ga, B andothers but not limited to these. A general formula for doped lithiumcobalt oxide would be LiCo_(1−p)D_(p)O₂.

Example 10

The CPF process can also be used to make other lithium metal oxides offormula LiMO₂ such as LiMn₂O₄, LiNiO₂, and other formulations of Example2, as well as the doped derivatives and coated derivatives of theformula LiM_(1−p)D_(p)O₂.

The anion may also be a polyanion such as oxyfluorides and others. Theseformulations will be then be variants of LiM_(1−p)D_(p)O_(2−x)F_(x) andthe like.

Starting materials for these would be chosen from their correspondingsalts, preferably oxides, carbonates, hydroxides, nitrates, acetates andothers that can be dissolved preferably under mild conditions of time,temperature and pressure, rendering easily scale-up to industrialproduction. Another specialized cathode is a core shell lithiumtransition metal oxide wherein a CPF prepared coating compound forms theshell of the lithium metal oxide core in order to improve surfacecharacteristics for better temperature stability, better structuralintegrity over longer cycles, and improved capacity.

The invention has been described with reference to the preferredembodiments without limit thereto. One of skill in the art would realizeadditional embodiments and improvements which are not specifically setforth herein but which are within the scope of the invention as morespecifically set forth in the claims appended hereto.

The invention claimed is:
 1. A method of forming a powder M_(j)X_(p)wherein M_(j) is a positive ion selected from alkali metal, alkalineearth metal or a transition metal; X_(p) is a monoatomic or a polyatomicanion selected from groups IIIA, IVA, VA, VIA or VIIA comprising:charging a reactor vessel with a first reactant comprising said Mj;forming a surface interface of said first reactant; adding a secondreactant comprising said Xp to said surface interface thereby inducing asurface reaction between said Mj and said Xp at said surface interfacethereby forming MjXp; drying said MjXp to obtain a dry powder; andcalcining said dried powder of said MjXp.
 2. The method of forming apowder M_(j)X_(p) of claim 1 wherein said surface interface is a bubble.3. The method of forming a powder M_(j)X_(p) of claim 1 wherein saidsurface reaction comprises a complexcelle.
 4. The method of forming apowder M_(j)X_(p) of claim 1 wherein at least one of said first reactantor said second reactant is a solution.